Smiler is a costumed criminal who ran a underground hideaway for fugitive criminals beneath Gotham City. His costume consisted of a lifelike but immobile latex mask that was frozen in a smile.
Roland Meacham appeared to be simply the public spirited head of the Committee to Preserve Gotham Village, an area of Gotham City under threat from developers. In fact, he was a criminal known as the Smiler (so called because his lifelike latex mask made him appear to be constantly smiling) who was trying to save the village in order to protect the subterranean sanctuary for criminal fugitives which he had built in the caves beneath it, where crooks on the run could hide out, get fake I.D's and watch crime movies in a private cinema. He was unmasked by Batman and Robin.
Smiler had invented a beam of radioactive phosphorus which, when applied to an enemy's forehead, left an invisible mark which could receive an 'energy signal' that would stop them in their tracks at Smiler's command.